Field of the Invention
The present invention relates to a monoclonal antibody which recognizes the lipopolysaccharide binding site of macrophage cell surface receptor CD14 and has binding activity to monocyte or macrophage cells, and to a process for producing the same.
It also relates to a method for suppressing the production of an inflammatory mediator in a mammal cell which comprises competitively inhibiting binding of the cell surface receptor CD14 with lipopolysaccharide.
When CD14, which is a cell surface receptor having high affinity for lipopolysaccharide (referred to as "LPS" hereinafter), recognizes a complex of LPS and LPS binding protein (referred to as "LBP" hereinafter) in serum (the complex of LPS and LBP is referred to as "LPS-LBP complex" hereinafter), it causes monocytes or macrophages to excrete various factors such as inflammatory cytokines including TNF and IL-6, and NO to the outside of the cells. It has been reported that these factors play extremely important roles in crisis and worsening of sepsis.
The soluble CD14 antigen may also relate closely to the pathology of sepsis, and various pathological analyses of sepsis utilizing antibodies to CD14 antigen have been attempted. For example, International Patent Application Un-examined Publication in Japanese (KOHYO TOKKYO KOHO) No. Hei 8-510909/1996 discloses an antibody produced by a hybridoma which was obtained by imunizing a mouse or a rabbit with a recombinant CD14 as an antigen. Further, International Patent Application Un-examined Publication in Japanese (KOHYO TOKKYO KOHO) No. Hei 5-501399/1993 discloses use of an anti-CD14 monoclonal antibody for the treatment of sepsis, which competitively inhibits the binding of LPS-LBP complex to CD14.
However, these known antibodies were produced by using a recombinant CD14 as an antigen, and therefore they have problems concerning their specificity. For example, they may not show affinity for actual antigens that are present on cellular surfaces in various forms, antibodies having desired recognition characteristics may not be obtained because the recombinant CD14 used as the antigen may denature during its purification, or other problems may arise. Therefore, they have been insufficient for the application to pathology analysis and treatment of sepsis.
Accordingly, the object of the present invention is to provide a monoclonal antibody recognizing the LPS binding site of the macrophage cell surface receptor, CD14, which is useful for pathology analysis and treatment of sepsis and the like.